docs: comprehensive v5.1.2 documentation update

This commit brings all documentation up to date with the current v5.1.2
codebase, addressing 12+ critical discrepancies and adding 2 major new
documentation files.

## Files Modified (18 documentation files):

### Root Documentation:
- README.md: Updated version badge (4.3.1 → 5.1.2), tool count (7 → 9),
  added viewer UI and theme toggle features, updated "What's New" section
- CHANGELOG.md: Added 8 missing releases (v4.3.2 through v5.1.2) with
  comprehensive release notes
- CLAUDE.md: Removed hardcoded personal paths, documented all 14 worker
  endpoints (was 8), added Chroma integration overview, updated v5.x releases

### Mintlify Documentation (docs/):
- introduction.mdx: Updated search tool count to 9, added viewer UI and
  theme toggle to features
- configuration.mdx: Added smart-install.js documentation, clarified data
  directory locations, added CLAUDE_CODE_PATH env var, explained observations
  vs sessions, updated hook configuration examples
- development.mdx: Added comprehensive viewer UI development section (103 lines),
  updated build output filenames (search-server.mjs)
- usage/search-tools.mdx: Added get_context_timeline and get_timeline_by_query
  documentation with examples, updated tool count to 9
- architecture/overview.mdx: Updated to 7 hook files, 9 search tools, added
  Chroma to tech stack, enhanced component details with viewer UI
- architecture/hooks.mdx: Added smart-install.js and user-message-hook.js
  documentation, updated hook count to 7
- architecture/worker-service.mdx: Documented all 14 endpoints organized by
  category (Viewer & Health, Data Retrieval, Settings, Session Management)
- architecture/mcp-search.mdx: Added timeline tools documentation, updated
  tool count to 9, fixed filename references (search-server.mjs)
- architecture-evolution.mdx: Added complete v5.x release history (v5.0.0
  through v5.1.2), updated title to "v3 to v5"
- hooks-architecture.mdx: Updated to "Seven Hook Scripts", added smart-install
  and user-message-hook documentation
- troubleshooting.mdx: Added v5.x specific issues section (viewer, theme toggle,
  SSE, Chroma, PM2 Windows fix)

### New Documentation Files:
- docs/VIEWER.md: Complete 400+ line guide to web viewer UI including architecture,
  features, usage, development, API integration, performance considerations
- docs/CHROMA.md: Complete 450+ line guide to vector database integration including
  hybrid search architecture, semantic search explanation, performance benchmarks,
  installation, configuration, troubleshooting

## Key Corrections Made:

1. ✅ Updated version badges and references: 4.3.1 → 5.1.2
2. ✅ Corrected search tool count: 7 → 9 (added get_context_timeline, get_timeline_by_query)
3. ✅ Fixed MCP server filename: search-server.js → search-server.mjs
4. ✅ Updated hook count: 5 → 7 (added smart-install.js, user-message-hook.js)
5. ✅ Documented all 14 worker endpoints (was 8, incorrectly claimed 6 were missing)
6. ✅ Removed hardcoded personal file paths
7. ✅ Added Chroma vector database documentation
8. ✅ Added viewer UI comprehensive documentation
9. ✅ Updated CHANGELOG with all missing v4.3.2-v5.1.2 releases
10. ✅ Clarified data directory locations (production vs development)
11. ✅ Added smart-install.js caching system documentation
12. ✅ Updated SessionStart hook configuration examples

## Documentation Statistics:

- Total files modified: 18
- New files created: 2
- Lines added: ~2,000+
- Version mismatches fixed: 2 critical
- Missing features documented: 5+ major
- Missing tools documented: 2 MCP tools
- Missing endpoints documented: 6 API endpoints

## Impact:

Documentation now accurately reflects the current v5.1.2 codebase with:
- Complete viewer UI documentation (v5.1.0)
- Theme toggle feature (v5.1.2)
- Hybrid search architecture with Chroma (v5.0.0)
- Smart install caching (v5.0.3)
- All 7 hook scripts documented
- All 9 MCP search tools documented
- All 14 worker service endpoints documented
- Comprehensive troubleshooting for v5.x issues

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

docs/usage/search-tools.mdx

@@ -1,11 +1,11 @@
 ---
 title: "MCP Search Tools"
-description: "Query your project history with 7 specialized search tools"
+description: "Query your project history with 9 specialized search tools"
 ---
 
 # MCP Search Tools Usage
 
-Once claude-mem is installed as a plugin, 7 search tools become available in your Claude Code sessions for querying project history.
+Once claude-mem is installed as a plugin, 9 search tools become available in your Claude Code sessions for querying project history.
 
 ## Quick Reference
 
@@ -18,6 +18,8 @@ Once claude-mem is installed as a plugin, 7 search tools become available in you
 | find_by_file            | Find observations referencing files          |
 | find_by_type            | Find observations by type                    |
 | get_recent_context      | Get recent session context                   |
+| get_context_timeline    | Get unified timeline around a specific point |
+| get_timeline_by_query   | Search and get timeline context in one step  |
 
 ## Example Queries
 
@@ -115,6 +117,70 @@ Get recent context for debugging:
 Use get_recent_context to show me what we've been working on
 ```
 
+### get_context_timeline
+
+Get a unified timeline of context around a specific point in time. This tool interleaves observations, sessions, and user prompts chronologically to show what was happening before and after a specific moment.
+
+**Anchor by observation ID:**
+```
+get_context_timeline with anchor=12345 and depth_before=10 and depth_after=10
+```
+
+**Anchor by session ID:**
+```
+get_context_timeline with anchor="S123" and depth_before=5 and depth_after=5
+```
+
+**Anchor by ISO timestamp:**
+```
+get_context_timeline with anchor="2025-10-21T14:30:00Z" and depth_before=15 and depth_after=15
+```
+
+**Use cases:**
+- Understand what was happening when a specific observation occurred
+- See the full context around a bug fix or decision
+- Trace the events leading up to and following a specific change
+- View chronological sequence of related work
+
+**Benefits:**
+- All record types (observations, sessions, prompts) in one chronological view
+- Configurable depth before/after anchor point
+- Flexible anchoring by ID or timestamp
+- See the complete narrative arc around key events
+
+### get_timeline_by_query
+
+Search for observations using natural language and get timeline context around the best match. This combines search + timeline into a single operation for faster context discovery.
+
+**Auto mode (default):**
+```
+get_timeline_by_query with query="authentication implementation"
+```
+Automatically uses the top search result as timeline anchor and returns surrounding context.
+
+**Interactive mode:**
+```
+get_timeline_by_query with query="authentication" and mode="interactive" and limit=5
+```
+Shows top 5 search results for you to manually choose which to use as timeline anchor.
+
+**Customize timeline depth:**
+```
+get_timeline_by_query with query="bug fix" and depth_before=20 and depth_after=10
+```
+
+**Use cases:**
+- Quick context discovery: "What was happening when we implemented X?"
+- Investigate issues: Find a bug fix and see what led to it
+- Decision archaeology: Search for a decision and understand the context
+- Feature timeline: See the complete story of a feature implementation
+
+**Benefits:**
+- Single-step operation (no need to search, then timeline separately)
+- Auto mode provides instant context
+- Interactive mode gives you control over anchor selection
+- Natural language search makes it easy to find relevant moments
+
 ## Search Strategy
 
 ### 1. Start with Index Format